Q&A: Turn Off The Lights?
By Jenn (TinyChoices.com) | February 12, 2008
Welcome to Tiny Choices Q&A, where we open the floor for discussion on questions which ya’ll have submitted (read the list of questions here, & add yours!)
Stacey asks:
Along the energy lines, I once heard that the amount of energy used to turn a lightbulb on is roughly equivalent to the amount of energy used by that same lightbulb in ten minutes and therefore, leaving a room for less than ten minutes, it made sense to leave the lightbulb on. Fact or fiction?
I think most of us have probably heard this question before and wondered if it’s true. Me, I’m a “lights off” kinda woman, even ducking into (empty!) conference rooms at work to switch off the lights as I walk by, and most certainly flicking the switch when exiting a single-stall public restroom. I do so because it just seems to make the most sense- why leave lights burning when they’re not needed, thus creating both extra demand for electricity and unnecessary pollution? But then again, what if Stacey is right, and I’m actually using more electricity by doing so? Yikes!
So I did some reading:
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Over at Grist, Umbra Fisk says: “Contrary to popular belief, turning lights on consumes no more electricity than they use when already lit. This is true for both fluorescent and incandescent bulbs. Out! Out!”
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On to Treehugger, where they say:
“The rule of thumb for optimizing the in-use versus turn-on power is:
* Standard incandescent: turn off even if you leave the room for just seconds.
* Compact fluorescent: turn off if you leave the room for 3 minutes.
* Standard fluorescent: turn off if you leave the room for 15 minutes.”
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Mythbusters tackled this question, and found that: “It’s best to turn off the bulb if you are leaving the room for”:
* Incandescent: 0.36 seconds
* CFL: 0.015 seconds
* Halogen: .51 seconds
* LED: 1.28 seconds
* Fluorescent: 23.3 seconds
“In other words, its almost always best to turn the bulb off. Even the 23 seconds for the fluorescent lights isn’t very long, and the rest of the times are pretty much blinks of an eye.”
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Over to the Energy Star website: “While there is a brief surge in energy use when a CFL is turned on, with today’s starting technology, that surge usually lasts about a tenth of a second and consumes about as much energy as five seconds of normal operation. So, even when turned on and off frequently, a CFL uses less energy than its incandescent equivalent. But because turning a CFL on and off more frequently can shorten its life and CFLs are more expensive than incandescents, we recommend consumers use CFLs in applications where they are on for at least fifteen minutes.”
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The verdict? Shutting off your lights definitely does conserve energy, though it might possibly shorten the lifespan of your CFL bulbs. So, for locations where the light burns for an average of 15 minutes or less (closets, maybe?) then it’s a toss-up between incandescents and CFLs. However, since incandescents are being phased out by 2014, better to get a head start now.
Tiny Choices PSA: CFLs contain mercury, which makes them too toxic to toss into your household trash. Lighter Footstep lists 5 ways to recycle CFLs when their lives are over, and when in doubt, Ikea takes back CFLs of all makes and models. If you find yourself with a broken CFL, here are the EPA guidelines on safely handling cleanup.
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Topics: Home, Q&A | 6 Comments »
6 Comments
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I know for me if I leave a light on because “I’ll be back in a second” I often end up forgetting that it is on. And then I come back an hour later! Therefore I save energy by always shutting the light off!
Thanks esp. for the PSA about disposal. We had a CFL go kaplooey last week and set it aside, not knowing how best to deal with it.
fantastic info, i had heard that line too. will you also (although you may not drive) do a rundown on idling cars? isn’t there a similar line about turning off the car only if it’s going to be more than x minutes? ie takes more gas to start the car than idle for a bit…tx…
Hey MamaBird- if you add your question to the queue, we’ll get to it as soon as we can!
this is a bit off topic, but related enough that i feel the need to post it…
another fact or fiction situation deals with cpus and monitors being turned off. if you are stepping away from your computer, if you simply switch off your monitor it’s like turning off a light when you leave the room (based on wattage used). moreover, while in the days of yore it could indeed deplete the lifespan of your computer by turning it on and off frequently, todays models (and dare I say since the 90′s) computers are not damaged by turning them on and off; so go ahead and turn that off too. the EPA has suggestions for length of time with which you should consider it, but i conducted some experimental watt measurements and the “surge” is not ginormous, so shut that bad boy off too.
Thanks so much, Michelle! That’s great info to have.